Texas health officials have confirmed the state's first case of chikungunya, a mosquito-borne illness newly emerging in the western hemisphere.

The patient, who lives in Williamson County near Austin, recently returned to Texas from a trip to the Caribbean, where the virus was detected late last year and now has been suspected or confirmed in about 135,000 people. It can cause severe joint pain and fever.

Public health officials are concerned the virus could explode in the United States because two mosquito species known to spread the disease are abundant here, including in Texas. So far, the only case of the disease transmitted on U.S. soil occurred in Puerto Rico.

The virus is considered less lethal than West Nile disease, also spread by mosquitoes. There is no known treatment. The joint pain can be excruciating, but most people feel better within a week. Other symptoms include muscle pain, headache, nausea, fatigue and rash.